How Not to Make a Wee Planet in GIMP

I was fooling around again recently with some "Wee Planet" stereographic panoramas (previously mentioned here), and came across some tutorials on doing this with Photoshop/GIMP using a Polar Coordinate distortion filter.

While this will give you a similar result to what you might see from a true stereographic projection, it is not quite as aesthetically pleasing I feel. This is because the Polar Coordinate transform is not a true stereographic mapping, and will tend to squish objects in a very non-pleasing way.

Notice how the Basilica is squashed in this view. In fact, all of the structures above the horizon have been seriously shortened. Because the polar coordinate transformation is essentially just remapping the image to a circle, notice also that the distance from the center to the outer edges is the same as the height of the source image.

Loading the image into Hugin, though, allows us to remap the output to a true stereographic projection:

Stereographic mapping in Hugin

The results here are much more aesthetically pleasing, in my opinion. The local angles are preserved, and the relative prominence of objects above the horizon become much larger.

In each of these cases I personally much prefer the stereographic projection.

The only drawback of this method is that it requires a full 360° × 360° full panorama of your scene (for best results). This is not always practical if you're shooting on the fly. If the scene you want to capture is intended to be a little planet, it's definitely worth the time to capture a full panorama to map stereographic.

I just discovered this myself and I completely agree. I'm new to making these little planets and was frustrated at how squished my planets were, since other ones I had looked at didn't have this problem. What's nice about this also is that it can all be done within Hugin! It really is a great piece of software.

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